When inlining allocations for Array and String iterators, make sure the
allocations have proper types on it (rather than just Type::Any). This
allows us to escape analyze the iterators in a couple of more cases,
i.e. in this very simple case:

  function f(a) {
    const it = a[Symbol.iterator]();
    return it.next().value;
  }

R=jarin@chromium.org
BUG=v8:4586,v8:5448

Review-Url: https://codereview.chromium.org/2640743003
Cr-Commit-Position: refs/heads/master@{#42449}